PHYSICAL AND CHEMICAL PROCESSES. 



in 



ash (to absorb all CO 2 formed, and thus allow a more active respi- 

 ration), keeping the peas from falling out by wire netting or the 

 tops of Zurich germinators (Fig. 28). Thrust accurate thermome- 



Fi<;. 28. SIMPLE ARRANGEMENT FOR STUDY OF HEAT-RELEASE IN GROWTH. 



One-fourth the true size. 



ters through the holes of the pots into the peas ; cover both with 

 close non-conducting hoods made of felt paper (Fig. 28), set in a 

 favorable place for growth, and observe the thermometers minutely 

 everv few hours. 



> 



What is the precise physical and physiological meaning of the 

 phenomenon shown? 



This may also be well tested by placing many rapidly-developing 

 flowers in a flask or wide-mouthed bottle, and noting the difference 

 between the temperature of a thermometer thrust among them in com- 

 parison with one in a similar vessel lacking the flowers. Of course this 

 must not be carried on in direct sunlight. Another excellent method 

 is that of placing a thermometer in the spathe of a rapidly opening 

 araceous flower such as Richardia or Symplocarpus, and comparing it 

 with another immediately outside. Since the temperature-differences 

 are slight, the more minutely the thermometers read, the better. An 

 elaborate and more exact method of investigating this subject is given 

 in Annales des Sciences Naturelles, Boturique, 1^93. 



